254 THE OCEHN WORLD. 
single orifice in the centre of the lower surface of the body, destitute 
of teeth, performing the functions both of mouth and anus. De 
Blainville says that “the liver is well marked and rather considerable 
in the star-fishes, forming bunches occupying the whole circumference 
of the stomach, and extending to the cavities of the appendages where 
these exist.” The mouth and gullet is admirably adapted for securing 
the testaceous molluscs and other substances on which they feed. 
Reproduction in the, Echinodermata appears to be moncecious. 
Ovaries'are, as far as is known, present in all the female forms.. They, 
vary in number in different species. The sexes are usually separate’: 
the young are produced by eggs, the embryo of which undergo im- 
portant metamorphoses. Immediately after birth, the young star-fishes 
have a depressed and rounded body, with four club- shaped appendages 
or ‘arms at their anterior extremity.’ When they area. little more’ 
developed, papilla may be observed on the upper surface, in fine. 
radiating rows: after. twelve days. the fine rays begin to increase, and 
after eight days more: two rows of feet, or ambulacra, are developed 
under each ray,‘which assist in the locomotion of the animal by 
alternate elongation and. contraction, performing also the office of 
suckers, Like most other of the lower animals, they have the power 
of rep1oducing parts of their bodies which may have been accidentally: 
destroyed. , 
' Most ‘star fishes have five perfectly equal arms. They.resemble a 
cross of honour, which has five branches. The star of the brawe, the 
star of honour—these somewhat trivial words recall, nevertheless, the: 
resemblance’‘which ‘exists between the two objects ; ; doubtless, man 
has here taken Nature for his copy. It must, however, be remarked: 
that, ‘thougl five i is the general number of arms in the starfish, this: 
number i is not constant ; it varies with different’ genera, species, and’ 
even with individuals. . The connection of the arms with the . disc. 
presents equally rematkable differences. In the genus Cwdcita, the! 
disc is so much developed that it constitutes, so to speak, the entire’ 
animal, whilst the arms form only very slight’ protuberances upon its 
circumference. In: the ‘genus’ Luzdia, on ‘the contrary, the ‘disc is 
‘reduced to a minimum, whilst the arms ate of great length, and very 
slender. 
' The colours of ‘the many’ species Be starfish vary greatly ; they: 
vary from a ‘pellowsstt “erey, ‘a yellow-orange, a gamet -red, to a dark. 
violet. se ia 
‘Star- fishes are eedutecy and essentially jnlisbitants of the sea; 
they are never met with in fresh water ; many of them dwell amongst 
the submarine plants, others are found on sandy coasts ; they generally 
